Can robot fish find pollution?

An old fisherman and his wife live on the shores of a polluted sea. Each morning, the gray-bearded angler rides out on the waves and casts his net, pulling in ever-dwindling hauls of fish. Then one day he catches something truly resplendent: a large fish of gleaming gold, speckled with scales of sapphire. What could this mean?

It may sound a bit like Alexander Pushkin's "The Tale of the Fisherman and the Fish," but this fictional encounter may soon be a possibilty. Only instead of offering wishes in exchange for its release, this golden fish will hunt down the sources of ocean pollution.

Developed by scientists at the United Kingdom's University of Essex, several of these $30,000 robotic fish dove into the waters off the port of Gijon in northern Spain in 2012. Once there, the bots began sniffing out and analyzing signs of pollution as part of the multiyear SHOAL research project funded by the European Commission and coordinated by the engineering firm BMT Group Ltd.

Examples of this fishy technology have already tested the waters of the London Aquarium, where they successfully swam free of human control. In addition, they didn't attract the attention of their flesh-and-blood predatory tank mates.

As the $30,000 robotic fish consists entirely of mechanical and electronic parts, it obviously wouldn't make for the most satisfying shark dinner -- nor would the old woman in Pushkin's story be able to do much with it in a stew. The real payoff to both humans and fish is the robot's potential to provide a real-time understanding of ocean pollution.

So why all the work to make it look like an animal? How do the fish bots report back to the researchers, and why aren't sharks interested in taking a bite?